Tucker, who was 15 at the time of the shooting, didn't know the gun was loaded, prosecutors said. The shooting occurred in December 2008 near Dauphin Island Parkway.

"The witnesses confirmed that he had, in fact, taken the magazine out, and it was not in at the time, which would lead him to think perhaps that it was not loaded," said Mobile County Assistant District Attorney Jo Beth Murphree.

At a Thursday sentencing hearing, Smith also granted Tucker credit for about two months of jail time that he's already served, according to court records.

James was an honor student at Williamson High School who aspired to join the Navy one day, family members have said.

Mobile police initially called the shooting accidental, but investigators later upgraded the charge against Tucker to murder.

At a bench trial earlier this month, prosecutors decided to pursue the lesser felony charge of manslaughter.

Smith then found Tucker guilty of criminally negligent homicide, a misdemeanor offense, according to court records.